Balancing device



Nov. 1, 1960 D. Hol-'MANN 2,958,165

BALANCING DEVICE Filed MayrlB. 1959 BALANCING DEVICE Donys Hofmann, Seeshaupt am Starnberger See, Germany Filed May 18, 1959, Ser. No. 813,893

Claims priority, application Germany May 24, 1958 6 Claims. (Cl. 51-169) The invention relates to a balancing device for rotary tools which are subject to wear, for example grinding wheels, in which an annular preferably dovetail-shaped groove may be provided in the face of a flange on each side of the tool for receiving adjustable weights to compensate for out-of-balance, additional unbalancing as occurring during operation as a result of wear of the tool being periodically balanced by smaller additional weights which are likewise displaceably secured to the flange.

It is generally known that the quiet running of circular rotating tools, such kas grinding wheels, polishing discs, emery wheels and the like, and hence the load on the bearings therefor as Well as the quality of the work carried out with these wheels, all depend on the precise balancing of the tool. For this reason, such wheels and discs are balanced by the manufacturers. However, as a result of wear, fresh out-of-balance occurs,` which, particularly at high tool speeds, leads to a considerable load on and wear of the main bearings of the grinding or like machine and a marked waste of power. When out-of-balance couples are exerted on, say, a grinding wheel during rotation, it tends to wobble to an extent permitted by its bearing clearance and this detrimentally affects the work carried out with the grinding wheel.

In order to lock the grinding wheel in its mounted position, it has been common to use a flange on each face of the wheel, an annular groove being provided in each such ange. This annular groove serves to receive balancing weights for compensating any unbalance found even before the grinding wheel is put to use. Fresh unbalance as occasioned during operation by virtue of wear of the grinding wheel is then removed by adjusting these same weights. However, this procedure is somewhat complicated because the comparatively large balancing weights as used to compensate the initial unbalance are too coarse for accurately compensating subsequent unbalance occurring during operation. Above all, since the displacement of a weight to a new balancing position leads to a lack of weight at the point from which it was displaced, there mus-t needs be prolonged trial and error before the weight is mounted in the correct position.

It has already been proposed to use hollow rings in which lead balls or shot Iare inserted in compartment to compensate unbalance, including that occurring during operation. Such hollow rings are, however, comparatively complicated and expensive to manufacture. In addition, the inserted lead balls tend to wear down comparatively quickly during operation. For these reasons, these known arrangements have so far not been widely accepted in practice.

According to the present invention, in a balancing device of the kind referred t at least one of the two anges comprises a groove in addition to the one usually provided, such additional groove being concentric and smaller in diameter and cross-section than the conventional groove, and housing at least two additional weights adapted to be displaced to compensate unbalance occurd, 2,958,155 Patented Nov.. l, 1960 ring spasmodically during operation. In a preferred form of the invention, the ratio of the cross-section of the smaller annular groove to that of the larger annular groove is between 1:2 to 1:10 and preferably between 1:3 to 1:5.

Thus, by means of the invention, unbalance in the rotary tool resulting from manufacture is compensated by a suitable arrangement of the larger balance weights in the wider outer annular groove. Any fresh unbalance arising as a result of the mounting and wear of lthe tool is periodically compensated by displacing the smaller balance weights in the additional inner annular groove of smaller cross-section. Accordingly, it is no longer necessary for the larger balance weights to be displaced every time a balancing operation is performed. The smaller balance weights can be displaced round the whole circumference of the inner annular groove independently of the larger balance Weights and thus without being hampered by the latter.

Preferred examples of the invention are illustrated in the accompanying drawing, in which:

Fig. l is a front view of a grinding wheel with a mounting flange according to the invention,

Fig. 2 is a section through the grinding wheel of Fig. l, and p Fig. 3 is a section through a modified embodiment.

A mounting ange 2 having a cylindrical sleeve 3 is inserted in the central bore in a grinding wheel 1, as

shown in Figs. 2 and 3. The grinding wheel 1 is secured by a nut 4 screwed onto the sleeve 3. A dovetailed annular groove 5 of relatively large cross-section and a dovetailed annular groove 6 of smaller cross-section are machined in the face of the flange 2. Two smaller balance weights 8 (Fig. 1) slide in the smaller annular groove, and each can be locked therein by means of a screw. Two larger balance weights 7 and 9 slide in the larger annular groove S. These can likewise be locked in their groove by means of a screw.

Any unbalance before use of the grinding wheel is rcmoved by suitable aljustment of the balance weights 7 and 9 in the annular groove 5. In order to compensate for out-of-balance occurring during operation as a result of the mounting and wear of the grinding wheel, the smaller balance Weights 8 are periodically adjusted in position within the smaller annular groove 6.

In the embodiment shown in Fig. 3, the nut 4 securing the grinding wheel 1 likewise comprises at least one annular groove 5 in which balance weights (not shown) such as 7 and 9 can likewise slide. In this manner, dynamic balancing of the grinding wheel on the two-plane principle is rendered possible. lf the users of the grinding wheels have dynamic balancing machines `available so that the grinding wheels can be constantly adjusted, the nut 4i may comprise a smaller annular groove (not shown) such as 6 in addition to the larger annular groove 5.

I claim:

1. A balancing device for rotary tools which are Subject to wear comprising a mounting liange having a cylindrical sleeve which is inserted in a central bore of the tool, two annular grooves of different cross-sectional area in the face of the mounting flange, which grooves are arranged in a common plane perpendicular to the axis of the tool and have diiterent diameters, at least one smaller balance weight slidably arranged in the groove having the smaller cross-sectional area, at least one greater balance weight slidably arranged in the groove having the greater cross-sectional area, means being provided for securing the balance weights in adjusted positions within the grooves.

2. A balancing device for rotary tools which are subject to wear comprising a mounting flange having a cylindrical sleeve which is inserted in a central bore of the tool, two annular grooves of different cross-sectional area in the 'tionalV areasof the grooves bei/ng'in the range-of` 1:2to 1:10, at least one smaller balance weight slidably arranged in the groove having-thel smaller cross-sectionalarea, at -least one greater balaneefweight slidably-:arrangediinthe groove having the greater cross-sectional areafmeans justeclipositions within the, grooves. Y

3. A balancing device for rotary tools which are-subject towearcomprising amounting flange havinga cylindrical sleeve which is inserted-in a central bore ofthe'tool,` two concentric annular grooves of different cross-sectionalarea lbeing provided for securing Vther'balance-weightsin eadv Y in the face of the mounting flange; the ratio ofthe ,cross- Sectional area vof theinner groovefto the, outergroove being from 1:3 to 1:5, atzleast'one smaller balanceweight slidablyv arranged inthe groove'having the smaller crosssectional area, at least one greaterbalancel weight slidably anrangedrin the groove having the greater cross-.sectional area, means being provided for securing the balance weights in adjusted positions within-the grooves.

4. A balancing device for rotaryV tools which are subject to wear comprising a mounting ange having a cylindrical sleeve which is inserted in a central bore of the tool, -two annular dove-tail-shaped grooves of substantially-different cross-sectiona1 areas in thev face of the mounting flange, which grooves are arranged in a common plane perpendicular to the axis of the tool and have different diameters,

Aat least one smaller balance weight slidably arranged'in the groove having the smaller cross-sectional area,` at least one greater balance weight slidably arranged in the groove having the greater cross-sectional area, means being provided forV securing the balance weights in adjustedpositions Within the grooves.

5. A'balancing device for rotary tools which are subject to wear comprising a mounting ange having a cylindrical sleeve which is inserted in a central bore of the tool, two

annular grooves of substantially different cross-sectional area in the face of the mounting flange, which grooves are arranged in a common plane perpendicular to the axis of the tool and have diierent diameters, the ratio of the cross-sectional areas being in the range of 1:3 to 1:5, at least one smaller balance Vweight slidably arranged in the groove having the smallerrorosS-sectional area, at least one greater balance` weightslidably; arranged in the groove having the greater cross-sectional area, a nut screwed on the unflangedy end ofJ-said cylindrical-l sleeve, ateleast one annular groove in the face ofthe nut, at least one other balance Weight; slidablyaarranged in saidgroove, means being provided for securing the balance Weights in adjusted-positions withfthe grooves.

6. A balancing devicefor rotary tools which are subject to wear comprising a mounting ange having a cylindrical sleeve which is inserted in a central bore of the tool, two concentric annular y grooves of dilferent cross-sectional area-in vvtl1e"face f-'tfhefrriounting-llange,v the ratioffot the cross-sectionalearea vof r-`the 'inner groovet to *the outer groove Abeingfrom 1":3 to 1:5, -two smaller-balancefw'eights separately. slidably arranged'inithe groove'fhaving lt'he smaller cross-sectional area,` two greater balance Weights separately slidably Varranged in thev groove-havingi'the greater cross-sectional v area;r :meansbeing provided -for securing thelbalance-weights in-adjusted positions within the'grooves.

References Citedin the file of this patent UNITED f STATES: PATENTS dei" 

